The present invention relates to an expansion valve for use in a refrigeration cycle of an air conditioner of a car or the like.
For example, Japanese Patent Laid-Open No. 8-152232 discloses an expansion valve comprising an expansion valve body and a separately formed functional component containing a diaphragm chamber, wherein the expansion valve is formed by assembling this separately formed functional component to the valve body. Further, a spring is disposed within a temperature sensing case, enabling the length between the spring receiver to be controlled using a screw mechanism. A similar expansion valve structure is disclosed in Japanese Patent Laid-Open No. 11-351440.
According to the expansion valve disclosed in above-mentioned Japanese Patent Laid-Open No. 8-152232, the screw mechanism is equipped to the mounting portion of the temperature sensing case, and a screw mechanism is further utilized for fixing the body of the functional member to the valve body, by which the overall structure of the expansion valve becomes complex.
The object of the present invention is to provide an expansion valve comprising a piping member and a cassette unit provided with the functions of the expansion valve, so that the overall structure of the expansion valve can be simplified greatly.
The expansion valve according to the present invention comprises as basic components a housing with a refrigerant path to which is connected a pipe communicated with various devices of the air conditioner, and a cassette unit inserted to the housing. The cassette unit comprises a flange member, a tube member formed integrally with the flange member, a guide member, an orifice member and a plate member fixed to an interior of the tube member, a valve member disposed within a valve chamber defined by the orifice member, a spring disposed between the adjustment plate member defining the valve chamber and the valve member, biasing the valve member toward the orifice member, a shaft member for driving the valve member, a lid member welded onto the flange member, a diaphragm sandwiched between the lid member and the flange member and defining a gas charge chamber, and a stopper for transmitting a displacement of the diaphragm to the shaft member. Moreover, the housing further comprises an internal thread formed to a bottom of an inner bore portion for mounting the cassette unit, and the cassette unit further comprises an external thread formed to an outer circumference of the adjustment plate member.